On the present research project the principal investigator proposes to continue his studies on the mechanisms involved on the healing-over process, the exchange of ions and molecules between normal and damaged heart cells as well as the influence of drugs and hormones on chemical sensitivty and on electromechanical properties of heart cells. BIBLIOGRAPHIC REFERENCES: Effect of intracellular injection of calcium and strintium on cell communication in heart. W.C. De Mello. J. Physiol. #250:231-145 (1975). Uncoupling of heart cells produced by intracellular sodium injection. W.C. De Mello. Experientia, 31: 460-461 (1975).